13. Periodic Interval Timer (PIT)

The PIT consists of a 20-bit counter running on MCK / 16. This counter can be preloaded with any value between 1 and 220. The counter increments until the preloaded value is reached. At this stage it rolls over and generates an interrupt. An additional 12-bit counter counts the interrupts of the 20 bit counter.

The PIT is intended for use as the operating system’s scheduler interrupt.